Treatment of source water

ABSTRACT

There is provided herein a system and method for de-toxifying and de-scaling source water. In some embodiments, source water will be mixed with either an aluminum source or an iron source to separate endotoxins from acidic proteins and convert the naturally present bicarbonate in source water to carbon dioxide. Endotoxins and carbon dioxide will then be removed from source water by a stage of hydrophobic membranes to produce de-toxified and de-carbonated source water. Calcium hydroxide will be mixed with the de-toxified and de-carbonated source water to form precipitates comprising foulants and sulfate. A recoverable and reusable amine solvent will also be used to induce efficient precipitation. Possible reuse applications for the treated source water by the inventive methods that minimize excessive uses of potable water may include hydro-fracturing of shale and sand formations and heavy oil recovery by steam injection.

BACKGROUND OF THE INVENTION Domestic Wastewater

Effluent Streams from Wastewater Treatment Plants (WWTP)

Domestic wastewater has diverse characteristics that vary by place andseason. The composition of wastewater comprises inorganics, organicacids, microbes, and traces of priority and emerging organic pollutants.WWTP may include: (1) a gathering and preliminary processing step forsewage influent; (2) a secondary step to degrade biodegradable species;(3) a filtration step to roughly polish the effluent; and (4) adisinfection step to reduce microbes' activities. The secondary step isbiological, which may be based on an activated sludge system, an aerobicgranular sludge system, a bio-membranes system, or other methods.Regardless of the nature of the biological step, WWTP partially removecontaminants. As a result, effluent streams from WWTP cannot be directlyused without further treatment, and thus they are often discharged intoreceiving surface waters. Among the species of concern in effluentstreams are organic content (OC), total phosphorus (TP), boron, andtraces of transition metals.

OC comprises natural organic materials (NOM), trace organic materials(TOM), and microbially produced organic materials (POM). NOM areoriginated from drinking water, which is the main source of domesticwastewater. NOM are typically dominated by humic substances. TOM includetraces of various priority and emerging organic pollutants such asendocrine disrupting compounds (EDC), pharmaceutically active compounds(PAC), personal care products (PCP) and disinfection by-products (DBP).

POM comprise extracellular polymeric substances (EPS). The formation ofESP may be controlled by different mechanisms including active cellssecretion, cells shedding, cells dissolution and hydrolysis, andadsorption from a surrounding environment. EPS matrices retain water,stick to surfaces, aggregate bacterial cells, stabilize aggregatedstructures, provide protective barriers for bacterial cells, absorbexogenous organics, accumulate enzymatic activities to digest exogenousorganics for nutrient possession, and bind with some polyvalent ions. Assuch, EPS are associated with both the solid phase as insolublematerials (e.g., colloids, slimes, and macro-molecules) and the liquidphase as soluble materials (e.g., dissolved micro-molecules smaller than0.45 μm).

The bulk of OC is biodegradable. The time to biodegrade OC varies withthe ability of bacteria to ingest it. Species with small molecularweights may be removed from wastewater immediately via the biologicalstep. Their removal may be completed in 1-2 hours. This group of readilybiodegradable species may be classified as “soft” organics. However,higher molecular weight species will take several hours to be degradedand removed. Yet, other species are more recalcitrant (e.g., EPS), andmay still be present in effluent streams after several days. Such lessreadily biodegradable species are of a particular interest since theyare challenging to biodegrade. Thus, OC in general, but it is EPScontent in particular, may be the most controlling factor in thebiological step.

OC is also a controlling factor in discharging effluent streams intoreceiving surface waters. Excess OC and TP (as a nutrient) in dischargedeffluent streams cause primary producers (e.g., algae, plankton andaquatic plants) in receiving surface waters to flourish. Primaryproducers pump oxygen into surface waters during the day but at nightthey remove oxygen. If “night-time” oxygen removal outpaces “day-time”oxygen replenishment, dissolved oxygen would be depleted. This processcauses rapid aging of receiving waters (eutrophication), and takes placein receiving surface waters often far down streams from where effluentstreams are discharged. Oxygen depletion in receiving surface watersalso takes place when secondary producers (decomposers of primaryproducers) remove oxygen faster than it can be replaced. Excess OC isusually the cause of this sudden flourishing of decomposers. Thedepletion of dissolved oxygen due to microbial blooms in this case takesplace close to discharging points of effluent streams. In eithersituation, aquatic life die once dissolved oxygen in receiving surfacewaters is depleted at a given time.

As such, either reusing or discharging effluent streams from WWTP are ofconcern. In order to control the biological step within WWTP thatcontrols the quality of effluent streams and/or to measure the oxygendepletion rate in receiving surface waters as a result of dischargingeffluent streams, some knowledge of OC load is essential. OC load istypically measured by three conventional parameters: total organiccarbon (TOC); chemical oxygen demand (COD); and biochemical oxygendemand (BOD). Based on the inventor's experience in treating domesticwastewater, FIG. 1 shows the relation among such parameters as relatedto OC.

One of the methods to measure OC is the total carbon (TC). TC is dividedinto two contents; inorganic carbon (IC) and TOC. TC may be commonlyanalyzed by two basic steps. In the first step, the IC content isremoved by acidifying (converting alkalinity to carbon dioxide) andpurging the sample to measure it's released CO₂ as IC. However, thesample purging not only removes the released carbon dioxide from the ICcontent but also removes volatile and semi-volatile organics. In thesecond step that follows the first one, the OC content may be chemicallyoxidized to measure it's released CO₂ as TOC. However, the oxidationefficiency varies with the makeup of OC in the sample. Persulfate, forexample, can chemically oxidize many organics but the oxidation is veryslow and time consuming (a trial-error procedure) since the molecularstructures of the OC makeup in the sample is stoichiometricly unknown topredetermine the proper oxidation time and/or the proper concentrationof the oxidant. More importantly, persulfate oxidizes organic acids (theoverwhelming portion of OC) very slowly and their oxidation is far fromcomplete. Further, the oxygen content of the released carbon dioxidefrom oxidizing OC is likely water derived since only a minor fraction oforganic acids may be oxidized. As such, IC content in domesticwastewater is always far higher than TOC content due to accurateaccounts for alkalinity but may also be due to a poor quantification ofOC (e.g., purging of volatile and semi-volatile organics and incompleteoxidation of organic acids).

OC can also be measured indirectly by quantifying the amount of oxygenneeded to chemically or biochemically (micro-organisms) oxidize OC. Oneof the basic measurements is oxygen demand, which is the total amount ofoxygen required to aerobically degrade OC. Oxygen demand is furtherdivided into COD and BOD. COD measures the amount of oxygen needed tochemically oxidize OC. BOD measures the amount of oxygen needed tobiochemically oxidize OC. However, biochemical oxidation is a very slowprocess and theoretically takes an infinite time to reach completion. Assuch, ultimate BOD (BOD_(u)) is measured by allowing the test to run aslong as dissolved oxygen can be removed from the sample (generally 30-60days). However, the most widely measured BOD is truncated after 5 days(BOD₅), which may correspond to about 55-70% completion of biochemicaloxidation. BOD₅ may be, to some extent, useful to measure the oxygendepletion rate in receiving waters caused by discharging effluentstreams from WWTP. But in order to measure the efficiency of thebiological step within WWTP where knowledge of the influent's organicload is required in a short period of time, BOD₅ is even of a morelimited value because of the required 5-days to make the measurement.Thus, short-term BOD (BOD_(ST)) that can be carried out in a short time(e.g., 30 minutes to several hours) may deficiently be used, instead ofBOD₅, to measure the influent's organic load.

Reject Streams from Wastewater Treatment & Reclamation Plants (WWTRP)

Since reusing and/or discharging effluent streams from WWTP into surfacewaters pose health and environmental risks, their reclamation isimperative. In addition, water shortage in some regions made theirreclamation a necessity to alleviate water stress. However, one of thecrucial health issues in reclaiming effluents streams from WWTP is theexistence of EPS (e.g., carriers for endotoxins). Knowing that it is notpossible to control EPS in the biological step, the removal of suchpollutants from effluents streams is critical to prevent contaminationof potable water resources. Thus, the integration of pressure-drivenhydrophilic membranes with WWTP has gained some attention to furtherreclaim effluent streams from WWTP.

WWTRP are based on integrating WWTP with hydrophilic membranes as areclamation part. The reclamation part may include microfiltration (MF)or ultra-filtration (UF) in conjunction with reverse osmosis (RO) ornanofiltration (NF) to improve the quality of effluent steams from WWTP.All of such membranes (MF, UF, NF, and RO) are hydrophilic. MF, UF andRO reject species larger than their membranes pores sizes (“sizeexclusion”) whereas NF rejects species based on both it is membranecharge and pore size (“charge and size exclusion”). UF or MF, as poroushydrophilic membranes, is aimed at removing colloids, suspendedparticles and pathogens including presumably bacteria, protozoan cystsand viruses. RO or NF, as tighter hydrophilic membranes, is aimed at theremoval of dissolved inorganics (NF partially removes monovalent ionsand some divalent cations), transition metals, phosphate, and some ofboron and dissolved OC.

Based on the inventor's experience in treating domestic wastewater, FIG.2 depicts a possible hypothetical flow diagram for a WWTRP. The WWTRPconsists of: (1) a pre-treatment setup that may include sewagecollection, screening, de-gritting/de-greasing, andchlorinating/de-aerating; (2) a biological setup that may be based onactivated sludge and sedimentation tanks; (3) an effluent streamgathering setup that may include collection tanks and screening; and (4)a reclamation setup that may be based on either MF or UF in conjunctionwith either RO or NF.

Product streams from WWTRP are usually diverted for “indirect potableuses” and/or “direct non-potable uses”. The “indirect potable uses” mayinclude: (1) storing water in groundwater aquifers for future use,replenishing groundwater aquifers, and/or mitigating seawater intrusionto coastal groundwater aquifers; and (2) blending with drinkingwater-supply resources (groundwater, rivers, lakes, etc.) before suchresources undergo further treatment.

The “direct non-potable uses” may include: (1) irrigation; (2) replacingpotable water as a feed water for cooling towers or as a make-up waterfor utility boilers; and (3) replacing potable water as source waterthat undergo further treatment to produce ultra-pure water forapplications such as nuclear power plants, semiconductors andelectronics.

However, the reclamation of effluent streams by such hydrophilicmembranes is not widely accepted by many regulating agencies despitetheir operations of many years for two critical reasons. The firstreason is that RO, NF or a combination of such hydrophilic membranespartially removes, for example, endotoxins from effluent streams. Thelevels of endotoxins in RO or NF product streams are much higher thanthe levels found in drinking water. Spreading endotoxins via thepractices of “indirect potable uses” to drinking water resources and/or“direct non-potable uses” to the food chain (via irrigation) is a majorhealth concern. EPS, as carriers for endotoxins, for instance, can passon many effects on water quality, and thus they remain the focal pointin ensuring public health. EPS also mask endotoxins from being properlyassayed (e.g., only after a total hydrolysis of proteins, endotoxins maythen be assayed) thereby masking endotoxins measurements. This mayexplain why endotoxins concentrations in laboratory reports areroutinely ignored or overlooked.

The second reason is that the production of “near distilled waterquality” (in terms of TDS; dissolved inorganics) from WWTRP is at theexpense of generating copious amounts of reject streams (at least 15% ofRO or NF feed stream) containing species mostly concentrated by aboutsix-fold. Discharging RO or NF reject streams from WWTRP into receivingsurface waters is thus far more riskier than discharging effluentstreams from WWTP. Recycling of such reject streams directly to sewernetworks or WWTRP influents is not possible since they contain highloads of OC and sulfate as well as transition metals that would impairthe biological step. Recalcitrant organic and sulfate overloads wouldoccupy a significant portion of dissolved oxygen; consequently inhibitboth active biomass yield and nitrification within the biological step.Disposal in deep wells may also be restricted due to possiblecontamination of shallow groundwater aquifers via geologicalconnectivity and leakage.

Whether using RO or NF product streams to replenish drinking watersupply resources, or discharging RO or NF reject streams into waterways, dilution with receiving waters is the underpinning theme. However,dilution is not the remedy to pollution since dilution only expandspollution. Quality is the key, which should be the rule not theexception, for protecting human health and the environment.

It should be pointed out that in low-permeability shale and tight-sandexploration, potable water is typically and preferably used to fractureand stimulate the formation [Bader, application Ser. No. 14/545,681].Each well may require between 1.7 and 4.2 million gallons (about6,400-15,900 m³) of potable water as a fracturing fluid. A portion ofthis fracturing fluid (e.g., may be 20-45%) flows back to the surface asproduced water. For example, produced water from the Marcellus basin wasover 1.3 billion gallons (4.9 million m³) in 2014 alone. Such astaggering volume of produced water indicates at least substantialpotable water dependency, if not overuse or depletion of potable waterresources that may compete with other uses especially in waterdistressed areas. During fracturing; however, organics and ions that mayinclude transition metals, scale-prone species, and Naturally OccurringRadioactive Materials (NORM) within formation layers are mobilized,mixed with high salinity downhole formation water, and brought to thesurface with produced water. Here, effluent streams from WWTP and/orhydrophilic membranes' reject streams (MF, UF, NF, RO, or a combination)from WWTRP may be used, due to mainly their low salinity, instead ofpotable water, but only after a rigorous treatment, in hydro-fracturing.Such derivative streams from WWTP and/or WWTRP may also be mixed withother harmful waste streams such as produced water (to reduce thesalinity of produced water), agricultural drainage water, mine drainagewater, and the like. Such mixed streams, and only after a rigoroustreatment, may then be used for fracturing to relief the overuse ofpotable water. These inventor's suggestions may provide plausible reusepaths for such harmful streams.

THE OBJECTIVES OF THIS INVENTION

The objectives of this invention are to provide Zero-Liquid-Discharge(ZLD) methods to directly reclaim effluent streams from WWTP and/orproperly amend WWTRP. Thus, this invention can be implemented tocompletely eliminate the use of pressure-driven hydrophilic membranes(MF, UF, NF, RO, or a combination), as the WWTRP ongoing but verylimited practice, by directly and independently treating effluentstreams and/or reject streams (sludge thickener, sludge de-watering, andsludge incineration) from WWTP. This invention can also be implementedto amend WWTRP by either: (1) treating RO or NF feed streams in WWTRP asan effective pre-treatment to produce amenable products streams as wellas amenable reject streams for direct reuse applications; or (2)treating reject streams resulting from MF, UF, NF, RO, sludge thickener,sludge de-watering, and sludge incineration in WWTRP as apost-treatment. Further, this invention can also be implemented fortreating mixed streams (e.g., mixing effluent streams from WWTP and/orhydrophilic membranes' reject streams from WWTRP with other wastestreams including produced water, agricultural drainage water, minedrainage water, and the like for reuse applications such as, but notlimited to, hydro-fracturing of shale and sand formations.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a method for treatingsource water. The inventive method comprises separating endotoxins andcarbon dioxide from source water by: (i) mixing either an aluminumsource or an iron source with source water to separate endotoxins fromacidic proteins and convert the naturally present bicarbonate in sourcewater to carbon dioxide; and (ii) removing endotoxins and carbon dioxidefrom source water by hydrophobic membranes to produce de-toxified andde-carbonated source water. The aluminum source is selected from thegroup consisting of aluminum chloride, aluminum chlorohydrate, aluminumnitrate, aluminum sulfate, aluminum acetate, aluminum formate, andcombinations thereof. The iron source is selected from the groupconsisting of iron chloride, iron chlorohydrate, iron nitrate, ironsulfate, iron acetate, iron formate, and combinations thereof. Themethod comprises separating endotoxins and carbon dioxide from sourcewater, wherein step (ii) further comprises separating foulants andsulfate by: (i) mixing calcium hydroxide with the de-toxified andde-carbonated source water to form precipitates comprising eithercalcium sulfoaluminate or calcium sulfoferrate in a precipitator unit;and (ii) removing the precipitates by a filter. Foulants comprisemagnesium, phosphates, extracellular polymeric substances (EPS), silica,boron, transition metals, and combinations thereof. The method comprisesseparating foulants and sulfate, wherein step (i) further comprisesmixing an amine solvent, and recovering the amine solvent by a gaswherein the gas is selected from the group consisting of nitrogen, air,water vapor, and combinations thereof. The amine solvent is selectedfrom the group consisting of isopropylamine, propylamine, dipropylamine,diisopropylamine, ethylamine, diethylamine, methylamine, dimethylamine,and combinations thereof.

In another alternative, the present invention provides a method fortreating source water. The inventive method comprises separatingendotoxins and carbon dioxide from source water by: (i) mixing calciumnitrate with source water to separate endotoxins from acidic proteinsand convert the naturally present bicarbonate in source water to carbondioxide; and (ii) removing endotoxins and carbon dioxide from sourcewater by hydrophobic membranes to produce de-toxified and de-carbonatedsource water. The method comprises separating endotoxins and carbondioxide from source water, wherein step (ii) further comprisesseparating foulants and sulfate by: (i) mixing either aluminum hydroxideor iron hydroxide with the de-toxified and de-carbonated source water toform precipitates comprising either calcium sulfoaluminate or calciumsulfoferrate in a precipitator unit; and (ii) removing the precipitatesby a filter. Foulants comprise magnesium, phosphates, extracellularpolymeric substances (EPS), silica, boron, transition metals, andcombinations thereof. The method comprises separating foulants andsulfate, wherein step (i) further comprises mixing an amine solvent, andrecovering the amine solvent by a gas wherein the gas is selected fromthe group consisting of nitrogen, air, water vapor, and combinationsthereof. The amine solvent is selected from the group consisting ofisopropylamine, propylamine, dipropylamine, diisopropylamine,ethylamine, diethylamine, methylamine, dimethylamine, and combinationsthereof.

In yet another aspect, the present invention provides a method fortreating source water. The inventive method comprises separatingendotoxins and carbon dioxide from source water by: (i) mixing an aminesolvent in an anionated form with source water to separate endotoxinsfrom acidic proteins and convert the naturally present bicarbonate insource water to carbon dioxide; and (ii) removing endotoxins and carbondioxide from source water by hydrophobic membranes to producede-toxified and de-carbonated source water. The amine solvent isselected from the group consisting of isopropylamine, propylamine,dipropylamine, diisopropylamine, ethylamine, diethylamine, methylamine,dimethylamine, and combinations thereof. The anionated form is selectedfrom the group consisting of chloride, chlorohydrate, nitrate, sulfate,phosphate, acetate, formate, and combinations thereof. The methodcomprises separating endotoxins and carbon dioxide from source water,wherein step (ii) further comprises separating foulants and sulfate by:(i) mixing calcium hydroxide, and either aluminum hydroxide or ironhydroxide with the de-toxified and de-carbonated source water toregenerate the amine solvent from it is anionated form and to formprecipitates comprising either calcium sulfoaluminate or calciumsulfoferrate in a precipitator unit; and (ii) removing the precipitatesby a filter. Foulants comprise magnesium, phosphates, extracellularpolymeric substances (EPS), silica, boron, transition metals, andcombinations thereof. The method comprises separating foulants andsulfate, wherein step (i) further comprises the step of recovering theregenerated amine solvent by a gas wherein the gas is selected from thegroup consisting of nitrogen, air, water vapor, and combinationsthereof. The recovered amine solvent is reacted with an acid to producethe amine solvent in the anionated form for reuse. The acid is selectedfrom the group consisting of hydrochloric acid, chloral hydrate, nitricacid, sulfuric acid, phosphoric acid, acetic acid, formic acid, andcombinations thereof.

In yet another aspect, the present invention provides a method fortreating source water. The inventive method comprises separatingendotoxins and foulants from source water by: (i) mixing an aminesolvent with source water in a first precipitator unit to form firstprecipitates comprising endotoxins and foulants; and (ii) removing theprecipitates by a first filter to produce de-toxified and de-fouledsource water. The method comprises separating endotoxins and foulants,wherein step (i) further comprises the step of recovering the aminesolvent by a gas wherein the gas is selected from the group consistingof nitrogen, air, water vapor, and combinations thereof. The aminesolvent is selected from the group consisting of isopropylamine,propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine,methylamine, dimethylamine, and combinations thereof. Foulants comprisemagnesium, calcium, carbonate, phosphates, extracellular polymericsubstances (EPS), silica, boron, transition metals, and combinationsthereof. The method comprises separating endotoxins and foulants,wherein step (ii) further comprises separating sulfate by: (i) mixingthe de-toxified and de-fouled source water with calcium hydroxide andeither aluminum hydroxide or iron hydroxide in a second precipitatorunit to form second precipitates comprising either calciumsulfoaluminate or calcium sulfoferrate; and (ii) removing the secondprecipitates by a second filter to produce de-sulfated source water.

Source water is selected from the group consisting of domesticwastewater, an effluent stream from a wastewater treatment plant, aneffluent stream from a wastewater treatment and reclamation plant, areverse osmosis reject stream from a wastewater treatment andreclamation plant, a nanofiltration reject stream from a wastewatertreatment and reclamation plant, an ultrafiltration reject stream from awastewater treatment and reclamation plant, a microfiltration rejectstream from a wastewater treatment and reclamation plant, sludgethickening/dewatering reject streams from a wastewater treatment plant,sludge thickening/dewatering reject streams from a wastewater treatmentand reclamation plant, produced water, agricultural drainage water, minedrainage water, and combinations thereof.

This invention is of particular interest in connection with applicationssuch as, but not limited to, wastewater; wastewater treatment;wastewater treatment and reclamation; treatment of contaminated waterresources such as surface water or groundwater by wastewater, derivativestreams resulting from wastewater treatment plants (WWTP) and/orwastewater treatment and reclamation plants (WWTRP); oil and gasproduction; saline water desalination; mining; geothermal power plants;flue gas desulphurization; gypsum production; coal or oil fired powerplants; boilers; cooling towers; agricultural drainage water; textile;treatment of contaminated water resources such as surface water orgroundwater by natural brine or waste streams resulting from all kindsof mining operations; and treatment of natural brine, produced water, orwaste streams resulting from all kinds of mining operations to preventcontaminating surface water or groundwater.

This invention is not restricted to use in connection with oneparticular application. This invention can be used, in general, for theeffective and selective removal of critical inorganic and organicspecies from different source water. Further objects, novel features,and advantages of the present invention will be apparent to thoseskilled in the art upon examining the accompanying drawings and uponreading the following description of the preferred embodiments, or maybe learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the organic content (OC) in wastewater and it isconventional surrogate parameters.

FIG. 2 illustrates a hypothetical flow diagram for a WWTRP.

FIG. 3 illustrates the fractionation and characterization of OC ineffluent streams.

FIG. 4 illustrates the flow diagram of the tested pilot plant by theinventor.

FIG. 5 illustrates a possible flow diagram for the invented methods.

FIG. 6 illustrates another possible flow diagram for the inventedmethods.

FIG. 7 illustrates a further possible flow diagram for the inventedmethods.

DESCRIPTION OF THE PREFERRED EMBODIMENT The Precipitation Concept

I have previously invented the Liquid-Phase Precipitation (LPP) processfor the separation of ionic species from aqueous streams. LPP is basedon mixing an aqueous stream with a suitable solvent at ambienttemperature and atmospheric pressure to form selective precipitates. Thesuitable solvents are those which have the capability to meet two basiccriteria.

The first criteria is the suitability to precipitate targeted ionicspecies (charged inorganics and organics) from aqueous solutions. Theselected organic solvent must be miscible with the aqueous phase. Ofequal importance, the targeted ionic species must be sparingly solublein the organic solvent. The addition of such a solvent to anionic-aqueous solution leads to the capture of part of the watermolecules and reduces the solubility of ionic species in the water whichform insoluble precipitates. The solubility of the targeted ionicspecies in the organic solvent is a critical factor in achieving thedegree of saturation. Therefore, solubility related factors such asionic charge, ionic radius, and the presence of a suitable anion in theaqueous solution play an important role in affecting and characterizingprecipitates formation.

The second criteria is suitability for overall process design. For easeof recovery, the selected solvent must have favorable physicalproperties such as low boiling point, high vapor pressure, high relativevolatility, and no azeotrope formation with water. From a process designstandpoint, the selected solvent must have low toxicity since traces ofthe organic solvent always remain in the discharge stream. Further, theselected solvent must be chemically stable, compatible, and relativelyinexpensive.

Several solvents have been identified for potential use in the LPPprocess. These solvents are isopropylamine (IPA), ethylamine (EA),propylamine (PA), dipropylamine (DPA), diisopropylamine (DIPA),diethylamine (DEA), and dimethylamine (DMA). However, IPA is thepreferred solvent in the LPP process. The preference of IPA isattributed to its high precipitation ability with different ionicspecies, favorable properties (boiling point: 32.4° C.; vapor pressure:478 mmHg at 20° C.); and low environmental risks.

Nitrogen (N₂) can form compounds with only three covalent bonds to otheratoms. An amine molecule contains sp³-hybridized nitrogen atom bonded toone or more carbon atoms. The nitrogen has one orbital filled with apair of unshared valence electrons, which allows these solvents to actas bases. As such, amines are weak bases that could undergo reversiblereactions with water or acids. However, when an amine solvent reactswith an acid, the unshared electrons of the amine solvent are used toform sigma bond with the acid, which would transform the amine solventinto an anionated form. For example, the reaction of isopropylamine withformic acid produces isopropylamine formate, wherein isopropylamine isthe amine solvent and formate is the anionated form. Amine solvents inanionated forms acts as weak acids. The anionated forms of the selectedamine solvents that are found useful in this invention include chloride,chlorohydrate, nitrate, sulfate, phosphate, acetate, formate, andcombinations thereof. The amine solvent can be regenerated from it isanionated form by treatment with a hydroxide source.

Improving the performance of LPP is always a target. One of theessential improvements is to minimize, if not eliminate, the use of theamine solvent. Inorganic additives can alternatively replace aminesolvents or can be used in addition to amine solvents to induceprecipitation of targeted species. The suitable inorganic additives forLPP are those that can form an insoluble inorganic-based compound oftargeted charged species in an aqueous stream. Such inorganic additivesshould preferably be recoverable and recyclable, useable as a usefulby-product, or produced locally from reject or waste streams. Also, suchinorganic additives should not, themselves, constitute pollutants.Several inorganic additives were indentified, developed, and tested forLPP.

A second targeted improvement for LPP is to produce controllableprecipitates that are uniformly distributed with high yield andpreferably in submicron sizes. Submicron precipitates are fundamentallystable and form spontaneously if a narrow resistance time distributionis improvised and/or a surface active agent (naturally existing orinduced) sufficiently acts as a dispersant to prevent immediateagglomeration of the newly formed precipitates. Submicron precipitatesare thus dispersed phase with extreme fluxionality. On the other hand,non-spontaneous unstable macro-size precipitates will form if givensufficient time to rest.

The state (stabile, metastabe, or unstable) of given precipitates can beexpressed thermodynamically by the Gibbs free energy relation asfollows:ΔG=ΔH−TΔS  (1)where ΔG is the free energy of precipitates (provided by, for instance,mechanical agitation or other means), ΔH is the enthalpy that representsthe binding energy of the dispersed phase precipitates in water, T isthe temperature, and ΔS is the entropy of the dispersed phaseprecipitates (the state of precipitates disorder). The binding energy(ΔH) can be expressed in terms of the surface tension (τ) and theincrease in the surface area (ΔA) as follows:ΔG=τΔA−TΔS  (2)When the introduced free energy into the aqueous stream exceeds thebinding energy of precipitates, individual precipitates are broken downand redistributed. In addition, when a surface active agent is presentin the aqueous stream as an effective dispersant, r is reduced and thusthe precipitates binding energy is diminished. Furthermore, part of theintroduced energy may not contribute to precipitates' deflocculating butit dissipates in the aqueous stream in the form of heat which reducesviscosity. All of these factors increase precipitates dispersion ordisorder (positive entropy). As such, the change in the entropy (ΔS)quantitatively defines precipitates dispersion (solvation).

The Compressed-Phase Precipitation (CPP) process is thus developed bythe inventor to achieve sub-micron precipitates in certain applications.CPP is conceptually similar to LPP in which the targeted ionic speciesmust be nearly insoluble in the amine solvent whereas the mother solvent(water) is miscible with the amine solvent. However, the difference isthat fluids in the CPP process can be subjected to pressure and/ortemperature manipulations, or fluids modifications to force unusualthermo-physical properties (e.g., exhibit liquid-like density but withhigher diffusivity, higher compressibility and lower viscosity).

The fast diffusion combined with low viscosity of a compressed aminesolvent into an aqueous phase produces faster supersaturation oftargeted ionic species, and their possible precipitation in the desiredand sub-micron and micron sizes. Thus, the precipitate's size, sizedistribution, morphology, and structure can be controlled. Achievingfaster supersaturation would, in turn, minimize the use of the aminesolvent, reduce the size of precipitation vessels (a very shortretention time), and allow the recovery of targeted ionic species in thedesired precipitates shape and distribution.

Several factors could influence the performance of the precipitationprocess. Among such factors are: (1) the chemistry of the aqueous streamalong with the identity and concentration of it is targeted species; and(2) the conditions under which precipitation is induced by mixing theadditive (an inorganic, an amine solvent, or both) with the aqueousstream.

Testing of Source Water

Effluent Streams Vs. Hydrophilic Membranes Reject Streams

As shown in FIG. 2, the effluent stream from the biological step is thefeed stream to the hydrophilic membranes (e.g., UF-RO), where the UF-ROmembranes constitute the reclamation part of WWTRP. Table 1, as anexample, presents the reported species concentrations in the effluentstream and the RO reject stream. Table 1 indicates that inorganicspecies are extensively analyzed whereas organic species are largelyignored.

The vast majority of inorganic species are nearly highly rejected (˜98%)by RO. Therefore, the differences in the concentrations of such highlyrejected inorganic species between the RO reject stream and the effluentstream seem consistent with the RO rejection rate at 85% recovery ratio(RR). RR is defined as the ratio of the product flow rate to the feedflow rate. As a result, the total inorganic content (in terms of TDS) inthe RO reject stream is higher than that in the effluent stream by oversix-fold. The ratio of inorganic scale-prone species (bicarbonate,sulfate, phosphate, magnesium, calcium, strontium, barium, transitionmetals and silica) to the total inorganic content in the effluent streamis about 37% (in terms of meq./L), which remains about the same in theRO reject stream. In terms of strictly the total inorganic content, theeffluent stream may seem naturally amenable for most reuse applicationswhereas the RO reject stream may require further treatment (depleting ofat least the inorganic scale prone species or nearly depleting theentire TDS) for most reuse applications.

At least four sparingly soluble inorganic compounds under certainconditions are prone to form scale deposits. These compounds comprisemagnesium hydroxide, calcium carbonates, calcium sulfates, and calciumphosphates. Some forms of the last three compounds exhibit inversesolubility limits with temperature at a certain temperatures range.Calcium phosphates and calcium sulfates scales, in particular, are verydifficult to mitigate by scale inhibitors. Within the membranesreclamation part of the WWTRP, calcium phosphates and calcium sulfatesare prone to build-up at the membranes surfaces. Their builds-up maycause severe pores blockages, hinder steady RR, and force frequentmembranes cleanup and/or shutdowns. Scale inhibitors are primitive innature with proven limited values in solving sulfates and phosphatesscale.

Phosphorus species are an essential nutrient to all living cells. Totalphosphorus (TP) in domestic wastewater comprises inorganic and organicforms. Orthophosphates (e.g., PO₄ ⁻³, HPO₄ ⁻², H₂PO₄ ⁻ and H₃PO₄) arethe inorganic form. Organic phosphates comprise a chain ofpolyphosphates (e.g., P₂O₇ ⁻³, P₃O₁₀ ⁻⁵, etc.) linked to an organiccarrier (e.g., nucleotides). Polyphosphates are high energy moleculesand their chain is connected by a reaction coupling with the organiccarrier. The main organic carrier is adenosine, which is adenine (abase) and ribose (a monosaccharide) held together by a N-glycoside bond.The chain of polyphosphates is linked to ribose by one polyphosphateester bond and two high-energy anhydride polyphosphate bonds, whichforms adenosine tri-phosphates (ATP). As the primary energy regulator ofall organisms, ATP may control the operation of the biological step byunhooking the last polyphosphate bond (adenosine di-phosphates, ADP) orthe last two polyphosphate bonds (adenosine mono-phosphates, AMP) onATP, and hooking back such a polyphosphate bond(s) to reform ATP.

The typical concentration of TP in influent wastewater may be 15-20mg/L. As an essential nutrient to organisms, the concentration of TP inwastewater is more than necessary for the biological step that may onlyutilize about 20-30% of TP. Controlling TP is thus critical not only toachieve an efficient operation of the biological step but also tominimize the impact of discharging effluent streams and/or RO rejectstreams on receiving waters.

Photosynthetic autotrophs (e.g., plants, algae and cyanobacteria) inreceiving waters require sunlight, a carbon source (e.g., carbon dioxideand bicarbonate that are naturally present in receiving waters), and thesame TP nutrient as the biological step (synthetic heterotrophs) in WWTPor WWTRP. As such, eutrophication is essentially driven by the amountsof TP and EPS in a discharged effluent stream or RO reject stream. Thebiological step partially removes TP and thus a significant amount of TPremains in the effluent stream (Table 1), yet RO at 85% RRre-concentrates TP in it is reject stream by about six-fold (Table 1),whereas algae and cyanobacteria in receiving waters flourish at aconcentration as low as may be 0.1 mg/L of TP. Thus, evidence ofdevastating effects where receiving waters have been subjected toeffluent and/or RO reject discharges is blatant.

POM (insoluble and soluble EPS) are microbially produced in thebiological step. A portion of POM settles out as sludge but some remainsuspended and dissolved in the effluent stream. As such, rigorousanalysis of the carried over OC with the effluent stream as well as thesettled sludge is of prime importance for at least two fundamentalfactors.

The first factor is the bio-polymeric nature and massive production ofEPS in the biological step. EPS may roughly constitute about 80% of thetotal biomass. The second factor is that bacteria grow in suspensionsince suspension, unlike sludge, does not hinder nutrients diffusion. Aproper sludge settling from the biological step occurs when bacteria arediminished or washed-out. These fundamental factors are critical tounderstand the fate and implication of EPS on the specific design andoverall performance of WWTP or WWTRP.

As given in Table 1, COD may be the only routinely measured parameterthat is blindly used to assess the overall OC load. COD may reflect, tosome degree, the overall OC load, particularly EPS, since they are themain controller of oxygen demand. The difference in COD values betweenthe effluent stream and the RO reject stream may primitively indicatethe collective abilities of the hydrophilic membranes (UF and RO) ofrejecting OC. A low overall OC rejection by such hydrophilic membranescan be inferred from the COD values. This low OC rejection precludes theproduction of acceptable quality reclaimed water (e.g., the RO productstream), re-concentrates OC in the RO reject stream, and thus reinforcesthe unsuitability of such hydrophilic membranes to reclaim effluentstreams since they are simply feed stream splitters. This means speciesin the feed stream are reduced in the product stream but concentrated inthe reject stream, the reduction/concentration factor between theproduct stream and the reject stream is governed by the membrane'srejection rate for each species and the permissible membrane's RR, andat least the reject stream requires a proper disposal path or a furthertreatment to render it harmless.

The non-volatile TOC in RO reject stream is, on average, 56 mg/L. EPS,as microbially produced materials, are net negatively charged organicacids. As noted earlier [0007], EPS may be poorly included in such TOCmeasurements. However, EPS are the dominant matrices that bind inorganicscale prone species, carry endotoxins, and promote bio-growth,bio-fouling, bio-foaming and corrosion.

Effluent streams from WWTP and hydrophilic membranes' reject streamsfrom WWTRP should not pose health and pollution threats. This impliesthat in considering any possible treatment for such derivative streamsof domestic wastewater, one should be prepared: (1) to design thetreatment method based not only on removing EPS (insoluble and soluble)and their precursors that further form other harmful by-products butalso on providing a stabilizing sink to contain them; (2) to utilizemore advanced analytical tools to intrinsically characterize EPSproperties and innovatively use such properties to contain them; and (3)not to rely on a blind lump sum parameter (e.g., TOC) that mighterroneously be assumed to provide collective information but “what is”and “what is not” included in such a parameter may not be obvious.

Fractionation of EPS using more advanced analytical techniques is thekey for useful characterization, which may pave the path for properlyreclaiming effluent streams. In one of the inventor's studies, thefractionation of OC using advanced methods (e.g., size-exclusionchromatography, ion-exclusion chromatography, anion-exchangechromatography, hydrophobic-interaction chromatography, gel-filtrationchromatography, etc.) along with appropriate analytical techniques isconducted to evaluate the actual roles of OC. As such, FIG. 3 depictsthe fractionation of carried over EPS with activated sludge effluentstreams.

EPS are made up of proteins, polysaccharides, lipids, nucleic acids, andhumic substances. Transported EPS with an activated sludge effluentstream thus represent complex matrices of multiple species that haveindividual characteristics (e.g., size, charge, acid-base interactions,hydrophobicity, hydrophilicity, etc.). However, they possess a netnegative surface charge at typical pH conditions found in activatedsludge.

Proteins are one of the most important fractions of EPS. Proteins playseveral key roles in the formation and aggregation of EPS. The firstrole is the direct binding of their copious negatively chargedhydrophilic amino acids (e.g., glutamic and aspartic acids) and divalentcations to stabilize EPS aggregate structures. The second role is thecontribution of hydrophobic amino acids by clustering with otherhydrophobic species. The third role is that extracellular proteins: (1)trap, bind and concentrate organics within the microenvironment of theembedded cells; and (2) slowly degrade polysaccharides that release ofbio-films.

EPS also contain humic substances in their structure. Humic substancesare hydrophobic species comprising carboxylic and phenolic acids.

Microbial polysaccharides also constitute a very important fraction ofEPS. Lipopolysaccharides (LPS), known as endotoxins, are mostly found inthe outer membrane of Gram-negative bacteria. They are the integral partof the outer cell membrane and are responsible for the functionality andstability of the bacteria. The general structure of all endotoxins hasthree distinct parts (a lipid A, a center core with an inner part and anouter part, and an O-antigen). Lipid A comprises a disaccharide ofglucosamine, which is partially phosphorylated and highly substitutedwith amide-linked and ester-linked long-chain carboxylic acids. The mostcommon amide-linked carboxylic acid is a 14 carbon chain, 3-acyloxyacylresidue. The ester-linked carboxylic acids tend to be more variablehaving saturated hydrocarbon chains with 12 to 18 carbons. Lipid A islinked to the inner part of a central core. The inner part of thecentral core is also partially phosphorylated and contains2-keto-3-deoxyoctonic acid (KDO) and heptose residues. The phosphategroups at lipid A and the inner part of the central core may be alteredwith ethanolamine, pectinose, and divalent cations in varying amounts.The outer part of the central core, which comprises hexose residues, isin turn linked to hydrophilic, water soluble, side chains (O-specificpolysaccharide chains; each chain comprises three to eightmonosaccharide units). Single monosaccharide units may also be alteredby glycosylation, acetylation, or sialyation. All endotoxic activitiesreside within lipid A and it is attached inner part of the central core.As such, active structural substitutions and alternations enableendotoxins to adopt to changing conditions without impairing theirviability and lethality.

The molecular structures of LPS are thus heterogeneous in terms of size,interaction, composition, substitution and alternation. Their peculiarflexible and diverse structures, and their broad spectrum of endotoxicactivities have made them the most harmful constituents in domesticwastewater and derivative streams resulting from treated and reclaimeddomestic wastewater. They have a hydrophilic (water soluble) head group(O-polysaccharide chains) at the outer structure and a tail group (lipidA and the inner part of the core). The tail group comprises neighboringcarboxylic chains and phosphate chains. At low pH, such chains are lessionized but the carboxylic chains are hydrophobic whereas the phosphatechains (e.g., H₃PO₄) may be hydrophilic, and therefore the tail groupmay be amphiphilic. By neutralizing the phosphate chains at low pH, thenaturally present divalent cations in wastewater have less availableinteraction sites, and thus act as mediators between only the negativelycharged carboxylic chains and proteins. As a result, the hydrophobicspecies in the tail group are driven toward a compact structure.However, under about the typical neutral pH conditions (e.g., 6.5 to7.4) in wastewater, carboxylic and phosphate chains are more ionized andthe phosphate chains (e.g., HPO₄ ⁻² and H₂PO₄ ⁻) tend to be hydrophobicdue to binding with the naturally present divalent cations inwastewater, and thus the tail group may be entirely hydrophobic. Here,divalent cations have more available interaction sites to bind both thenegatively charged phosphate and carboxylic chains with proteins.

The unique nature of LPS controls their binding, aggregation (micellesand vesicles) and disaggregation (monomers) in proteins-rich wastewater,which may be illustrated as follows:

Upon folding in wastewater under the typical pH conditions (e.g., 6.5 to7.4), the hydrophobic tail group forms a shielded core within proteinsby clustering the hydrophobic side chains of proteins with carboxylicchains of lipid A and binding divalent cations (magnesium and calcium)that naturally present in wastewater with the phosphate bearing hydroxylgroups of lipid A and it is attached inner core. The overwhelminglyhydrophilic outer structures of both proteins (hydrophilic amino acids)and LPS (O-polysaccharide blocks) allow such outer structures toamicably bond with the hydrogen molecules (water soluble) in wastewaterwhile endotoxins are shielded as a caged core from interactions with thesurrounding aqueous phase. Although endotoxins are shielded; however,they may be continuously and slowly liberated in the form of monomers(disaggregates) into the surrounding aqueous phase by: (1) dissolutionwhen proteins comprise a higher fraction of EPS due to lyase enzymes ofproteins (e.g., in sludge); and (2) hydrolysis when polysaccharidescomprise a higher fraction of EPS (e.g., in effluent streams); though itmay be less pronounced if EPS comprise of more proteins but lesspolysaccharides (e.g., in sludge).

In order to preliminary evaluate the removal of EPS from an activatedsludge effluent stream, the inventor has initially tested two parallelsets of hydrophilic membranes-based reclamation systems (UF-NF andUF-RO). The activated sludge effluent stream is treated by UF at 90% RR.The nominal molecular weight cut off (MWCO) of the UF hydrophilicmembrane is 50 k Daltons (Da); ˜0.02 μm nominal pore size. The UFproduct stream is then treated by two parallel sets of NF and ROhydrophilic membranes, and each of the NF and RO set is conducted at 85%RR. The nominal MWCO of the NF membrane is 0.2 kDa; ˜0.001 μm nominalpore size. The membranes testing setups (UF-NF and UF-RO) are alsodepicted in FIG. 3. The main findings of the inventor's study aresummarized as follows.

The hydrophilic portion of OC is fractionated by a size-exclusionchromatography into four groups based on their molecular weights: (1)polymeric species that include proteins and building blocks ofpolysaccharides with molecular weights greater than 20 kDa; (2) humicsubstances with molecular weights between 0.5 and 1 kDa; (3) breakdownproducts (proteins, building blocks of polysaccharides, and humicsubstances) with molecular weights between 0.3 and 0.5 kDa; and (4)lower molecular weight species (<0.3 kDa) including individual monomericLPS molecules and disinfection by-products (DBP). On the other hand, thehydrophobic portion of OC is accounted for by a hydrophobic-interactionchromatography.

The average rejection of polymeric species by UF is about 81%. However,the average rejection of endotoxins by UF is about 50%. LPS in theeffluent stream may be complex molecules (micelles or vesicles) and/orbi-layer monomers with a wide range of molecular weights that mayapproximately extend between 0.3 and 150 kDa. Such a range of molecularweights extends from well below to well above the MWCO of UF, whichwould explain, in part, the low rejection of endotoxins by UF.

The hydrophobic fraction is about 8% of the total OC. The average UFrejection for the hydrophobic fraction is about 56%.

The rest of the hydrophilic groups are nearly completely transportedwith the UF product stream since their molecular weights are well belowthe MWCO of the UF membrane, and thus UF is incapable of rejecting suchgroups. The NF and RO rejection for the rest of such hydrophilic groupsvary based on the molecular weights of each group; decrease with thedecrease in their molecular weights. The difference between therejection abilities of NF and RO is nearly insignificant, and thevariations in their rejection are within the uncertainties of analyticalinstruments. The NF and RO rejection of humic substances, breakdownproducts, and lower molecular weights species are about, respectively,80-85%, 49-56%, 40-47%. On the other hand, the rejection of thehydrophobic fraction by NF and RO is near complete (>99%).

It is interesting to note that the rejection of endotoxins by the NF andRO hydrophilic membranes is about 81-83%. This falls within therejection range of species with molecular weights above 0.5 kDa. Sinceproteins-endotoxins interactions in wastewater shield endotoxins fromthe surrounding aqueous phase, the separation of endotoxins is thereforelargely coupled with the separation of proteins. However, the removal ofendotoxins by NF and RO membranes is far from complete even though themajority of their proteins carrier may fall within or above the nominalpore sizes of NF and RO membranes, especially the RO membrane. Thefragmentation of endotoxins, which may be due to their active shedding,their slow but continuous release from proteins into the aqueous phase,the turbulent flow at the membranes surfaces, fragments (bio-films)built-up at the membranes surfaces and fragments aging within themembranes pores, precludes sufficient removal of endotoxins by“size-exclusion”. As such, fragments of endotoxins can easily passthrough the NF and RO hydrophilic membranes and transport within the NFor RO product stream.

The standard unit for reporting endotoxins is the Endotoxin Unit (EU),which is equivalent to 0.1 ng. The typical range of endotoxins indrinking water is 1-50 EU/ml. However, the concentrations of endotoxinsin the tested NF and RO: (1) product streams are 130-210 EU/mL(13,000-21,000 ng/L); and (2) reject streams are 4,250-6,500 EU/mL(425,000-650,000 ng/L). It is worth noting that a pyrogenic reaction maybe caused by only a small concentration of endotoxins (as low as 0.1ng/kg of body weight).

The above discussed testings by the inventor are aimed at thefractionation of OC in the activated sludge effluent stream as well thebasic performance of the reclamation hydrophilic membranes (UF-RO andUF-NF) for removing OC from the effluent stream. However, furtherconsiderations are given by the inventor to the effect of recycledreject streams (UF reject and/or sludge thickener and de-wateringrejects), which is the ongoing practice in WWTRP, on the performance ofthe biological step that to some extent controls the levels ofendotoxins in the effluent stream. As such, a pilot plant testing isconducted by the inventor as shown in FIG. 4 to reflect the actualperformance of WWTRP and WWTP with such typically recycled rejects tothe influent stream. The WWTRP includes the hydrophilic membranes-basedreclamation part (UF-RO) whereas the WWTP does not. The gathered pilotplant data are then employed by the inventor to scale up WWTRP and WWTPto treat 375,000 m³/day of influent. Based on the pilot data, Table 2shows the projected levels of endotoxins in WWTRP and WWTP, whichreflects the ongoing practice with such recycled reject streams.

As depicted in FIG. 4 and presented in Table 2, the typically recycledreject streams in the WWTRP increase the influent daily load ofendotoxins (EU/day) by 112% (93% by the UF reject, 16% by the sludgethickener reject, and 2.5% by the sludge de-watering reject). Therecycled UF reject is by far the highest contributor that elevates theload of endotoxins not only in the mixed influent but also indirectly inthe rejects from the sludge thickener (e.g., an aerobic digester) andsludge de-watering. Thus, the daily load of endotoxins in the mixedinfluent is over two-fold the daily load of endotoxins in the influent.As a result, the daily load of endotoxins in the effluent is higher thanthat in the influent by 70%. The daily load of endotoxins in the ROproduct is 10% of that in the influent, but the level of endotoxins iseight-fold higher than the presumed maximum level of endoxtins indrinking water (e.g., 50 EU/ml). On the other hand, the daily load ofendotoxins in the RO reject (15% of RO feed) is about two-thirds (66.4%)of that in the influent. As such, discharging 56,250 m³ per day (14.9million gallons per day) of the RO reject in term of endotoxins isequivalent to directly discharging 248,800 m³ per day (65.7 milliongallons per day) of sewage influent into receiving waters.

As also presented in Table 2 (FIG. 4), the typically recycled rejectstreams in the WWTP increase the influent daily load of endotoxins byabout 9% (8% by the sludge thickener reject, and 1% by the sludgede-watering reject). As such, the daily load of endotoxins in the mixedinfluent is higher by about 9% than that in the influent. However, thedaily load of endotoxins in the effluent is lower than that in theinfluent by about 24%.

It is interesting to note that the daily load of endotoxins in theeffluent of WWTP as the final product is practically equivalent to thatin the final products of WWTRP (the combined RO product and rejectstreams) even though the daily flow of the WWTP effluent is slightlyhigher (by 1000 m³ per day or 264,200 gallons per day) than the dailyflow of the RO feed (the UF product). Hydrophilic membranes are veryvaluable systems when deployed properly, but here, there is clearly noadvantage for adding such elaborate and expensive hydrophilic membranes(e.g., UF-RO) as a reclamation part to further treat the effluent streamin terms of endotoxins. This is the same fundamental observation thatwas made by the inventor in 1987 (about 30 years ago) when theintegration of such hydrophilic membranes with WWTP was an idea at theinfant stage. Nowadays, a few WWTRP are implemented but not acceptedsince, as revealed above, such hydrophilic membranes do nothing morethan re-distribute endotoxins between their product streams and rejectstreams. Thus, they are not ZLD systems, and require further treatmentnot only for their reject streams but in fact for their both product andreject streams.

Table 3 shows the distribution levels of endotoxins when the biologicalstep is independently operated from the integrated UF-RO hydrophilicmembranes reclamation part of WWTRP. This means that only the thickenerand de-watering rejects are recycled to the influent (as is the casewith most WWTP) but the UF reject stream is not recycled to the influent(as is not case with ongoing practice of WWTRP). The daily load ofendotoxins in the RO product is about 6% of that in the influent butwith a significant lower daily flow (about 23% less than the influentdaily flow), and still the level of endotoxins is higher by five-foldthan the presumed maximum level of endoxtins in drinking water. On theother hand, the daily flow and the daily load of endotoxins in thecombined rejects (UF and RO reject streams) are about, respectively, 24%and 71% of the influent. Both UF and RO reject streams are heavilyinfested with endotoxins but the UF reject is the largest contributoreven though it is daily flow is about 43% of the daily flow of thecombined reject streams. Thus, discharging 88,400 m³ per day (23.4million gallons per day) of such combined rejects in term of endotoxinsis equivalent to the discharge of 266,250 m³ per day (70.3 milliongallons per day) of sewage influent into receiving waters.

When the WWTRP is operated without recycling any reject to the influent,as also presented in Table 3, the daily load of endotoxins in theeffluent without recycling any reject is lower than that in the influentby about 33%. The daily load of endotoxins in the RO product is about 4%of that in the influent but with a significant lower daily flow (about27% less than the influent daily flow), and still the level ofendotoxins is higher by four-fold than the presumed maximum level ofendoxtins in drinking water. On the other hand, the daily flow and loadof endotoxins in the combined rejects (RO reject, UF reject, thickenerreject, and de-watering reject) are about, respectively, 25% and 70% ofthe daily flow and load of endotoxins in the influent. The maincontributors for endotoxins in the combined rejects are the UF and ROrejects, and the thickener and de-watering rejects slightly reduce thedaily load of endotoxins in the combined rejects. As such, discharging94,300 m³ per day (24.9 million gallons per day) of the combined rejectsin term of endotoxins is equivalent to the discharge of 262,500 m³ perday (69.4 million gallons per day) of sewage influent into receivingsurface waters.

While the limitation of water resources is one of the main motivationsfor treating and reclaiming domestic wastewater, the harmful effects ofendotoxins load on water reuse as well as water discharge into receivingwaters are exceptionally and totally ignored, when the removal ofendotoxins must be the rule not the exception. The harmful effect of theremaining TP load, which causes eutrophication in receiving waters, isalso largely ignored. However, the removal of excess TP is presumablyattempted by alternating exposure of phosphates accumulating bacteriawithin the biological step to anaerobic (primary sedimentation tanks)and aerobic zones (activated sludge and secondary sedimentation tanks).It is based on the reaction coupling of ATP by operating in the ATPhydrolysis direction, using ATP generated by fermentative bacteria toprovide a proton gradient (energy) to drive nutrient accumulation andmaintain ionic balance. When bacterial cells require energy, one of thehigh-energy polyphosphates bonds is broken down, and thus ATP istransferred to ADP. When bacterial cells build-up so much energy, thenADP is reconverted to ATP. This reversible reaction coupling may besimplified as follows:

where PP_(i) is polyphosphates and H⁺ is the excess positive charge (theproton gradient).

Since ATP is an energy-coupling agent, energy cannot be stored butrather is produced by one set of reaction and is almost immediatelyutilized by the reversed reaction set. In the anaerobic zone, soluble OCis fermented by fermentative bacteria to produce a variety of volatilecarboxylic acids. Phosphates accumulating bacteria immediately absorband polymerize the fermentative carboxylic acids (e.g.,hydroxyalkanoates) but cannot degrade them under the anaerobiccondition. The polymerization of the carboxylic acids requires moreenergy, which is supplied by breaking down one of the high-energypolyphosphate bonds of ATP, releasing ADP, a chain of pyrophosphates andenergy. The released bond of pyrophosphates is then broken down by aninorganic enzyme (polyphosphatase) to form orthophosphates. Theanaerobic zone is thus supplied with two sources of orthophosphates, oneis naturally present in the influent and the second one is concurrentlyproduced by unhooking a bond of polyphosphates from ATP and breakingthem down to orthophosphates. In the aerobic zone, bacteria utilizeoxygen to degrade the fermentative carboxylic acids as a carbon sourceand thus energy is released. The released energy is consumed byabsorbing some of the available orthophosphates (naturally present inthe influent and produced in the anaerobic zone) to regenerate thebroken bond of pyrophosphates to be hooked to ADP, and thus ATP isre-formed. A portion of the elevated concentration of TP is removed withthe discharge sludge from the second sedimentation tanks (the final stepof the aerobic zone) where the sludge is further subjected to thickeningand dewatering. Reject streams from the sludge thickener andde-watering, which are decanted streams, are recycled to the firstsedimentation tanks (the anaerobic zone) to repeat the process ofexposing bacteria to alternating anaerobic and aerobic conditions.However, this process particularly in WWTRP, as confirmed by theinventor's pilot testing, is operationally unstable and only removed, onaverage, about 40-48% of TP from the mixed influent.

The relatively low and unstable removal of TP may be attributed to therecycling of the reject streams to the influent, particularly the UFreject stream since is heavily infested with endotoxins. InGram-negative bacteria, polysaccharides are built by the linkage of twoor more monosaccharides (sugars) by O-glycosidic bonds since sugarscontain many hydroxide groups. Polysaccharides play vital roles not onlyin maintaining the structural integrity of Gram-negative bacteria butalso in energy storage. As such, the excessive levels of Gram-negativebacteria (endotoxins) in the recycled UF reject stream to the anaerobiczone when subjected to a sudden and strenuous activity, the glycolysisof glycogen (release of glucose) can provide energy in the absence ofoxygen and can thus supply energy for anaerobic activity without usingpolyphosphates (not to break one of the ATP high-energy polyphosphatesbonds). This may explain the partial release of orthophosphates in theanaerobic zone.

The alarming levels of endotoxins in all outputs resulting from thetreatment of domestic wastewater, if not managed responsibly, would poseserious health and pollution risks. An example of such risks is the useof hydrophilic membranes (e.g., RO or NF) product streams to augmentgroundwater aquifers and potable water reservoirs, which are directpaths for endotoxins to drinking water supplies. Another example of suchrisks is the use of effluent streams and/or hydrophilic membranes (e.g.,RO or NF) product streams as irrigation water (as well as sludge as afertilizer) for applications such as agriculture and animal feed crops,which is an indirect path for endotoxins to the food chain. Airborneendotoxins also cause respiratory problems, fever and fatigue.Inhalation of moisture-laden air containing endotoxins viaaerosolisation of effluent streams and/or hydrophilic membranes productstreams (e.g., recreational irrigation, cooling towers, humidifiers,fire fighting, car washing facilities, etc.) and via venting fromdehumidifiers (e.g., the membranes-reclamation part of WWTRP istypically housed in a closed shelter that requires dehumidification) aredirect paths for airborne endotoxins. Yet, a further example of suchrisks is the discharge of effluent streams and/or hydrophilic membranesrejects streams into receiving waters, which is also an indirect pathfor endotoxins to source water. If, for instance, seawater is used assource water for producing drinking water in some coastal areas,thermal-driven seawater de-salting methods at their top temperature(<110° C.), would neither destruct nor separate endotoxic fragments, andthus endotoxins are carried over with their produced drinking water.Similarly, hydrophilic membranes such as RO are also ineffective inseparating endotoxic fragments from nearly proteins-free seawater by“size exclusion”.

Endotoxins act against cells or organs via activation of the immunesystem (e.g., the macrophages, lymphocytes, and monocytes). Their potentendotoxic activities are released through mediators (e.g., interleukins,prostaglandins, colony stimulators, tumor necrosis, platelet activatorsand free radicals). Endotoxins have strong effects at very low levels inhumans and animals when entering the blood stream by affecting thestructure and function of cells and organs, changing metabolicfunctions, triggering hemostasis via platelet adhesion and coagulation,altering hemodynamics, raising body temperature, and causing shock. Yet,endotoxins are notoriously resistant to destruction by heat (stable at120° C.), desiccation, pH extremes and various disinfection methods.Some of these methods may only kill live bacteria but none altersendotoxic activities of pyrogens, and thus dead bacteria would remain asource for pyrogens if not physically separated. Disinfection may be theonly practical option in wastewater treatment, and chlorination may bethe most practiced disinfection method. As confirmed by the inventor'stesting; however, chlorination does not reduce endotoxic activities inneither effluent streams nor RO reject streams, and increasing neitherthe chlorination dose nor the chlorination contact time can reduceendotoxic activities. Because of their high toxicity and adverseeffects, endotoxins remain a high health risk in treated or reclaimeddomestic wastewater. Their removal is thus essential for both safe reuseand discharge of derivative streams resulting from treating (e.g.,effluent streams) and reclaiming (e.g., both RO product and rejectstreams) domestic wastewater. However, an effective general method forthe removal of endotoxins from proteins-rich wastewater (or may be anyother proteins-rich solutions) is not available.

The proteins-endotoxins interactions largely shield endotoxins from thesurrounding aqueous phase but also slowly release endotoxins into theaqueous phase. Such interactions either (1) force the separation ofendotoxins via coupling with proteins as a carrier for endotoxins, whichis attempted by hydrophilic membranes (MF, UF, NF and RO), but asdemonstrated above such membranes, individually or in a combination, arenot only incapable of sufficiently removing endotoxins to an acceptablelevel in their product streams but also dangerously concentrateendotoxins in their reject streams; or (2) render the separation ofendotoxins from proteins as a complex and difficult task especially inlarge scale applications. It must thus be emphasized that there is adistinct difference between separating endotoxins from a proteins-richaqueous phase (e.g., domestic wastewater) and separating endotoxins froma nearly proteins-free aqueous phase (e.g., potable water or seawater).In the later case, hydrophilic membranes including RO have littleeffects on removing endotoxic fragments by “size exclusion”.

Treatment of Source Water

Based on the inventor's fractionation and distribution of proteins, thedata reveal proteins comprise 70-80% (73% on average) as acidic(negatively charged) hydrophilic proteins with an average isoelectricpoint of about 5.5, and the remaining as mainly basic (positivelycharged) hydrophobic proteins with an average isoelectric point of about9.2. Such distributions of proteins are nearly the same in effluentstreams and in sludge (WWTP, FIG. 4) even though the concentration ofproteins in sludge is over two orders of magnitude higher than that ineffluent streams. As such, proteins are net negatively charged under thetypically about neutral pH (e.g., 6.5-7.4) conditions in wastewater.Endotoxins are also negatively charged. Acidic proteins interact withendotoxins via mediators including the naturally present divalentcations (calcium and magnesium) in wastewater whereas basic proteinsinteract with endotoxins via both direct charge attractions and thestrong tendency of hydrophobic groups to be excluded from water byclustering rather than extending into the aqueous phase. In order toseparate the majority of proteins (acidic) that masks and cagesendoxtoins within their inner structures, the phosphorylated parts ofendotoxins and acidic proteins must be neutralized preferably byreducing the pH to within the isoelectric point of acidic proteins.

As such, in one embodiment of this invention, endotoxins are separatedfrom acidic proteins in source water by using either an aluminum sourceor an iron source to reduce the pH of source water to within theisoelectric points of acidic proteins. An additional innovative purposefor the use of either the aluminum source or the iron source is toconvert the naturally present bicarbonate in source water to carbondioxide. The separated endotoxins and the converted carbon dioxide arethen removed from source water by hydrophobic membranes to producede-toxified and de-carbonated source water. Yet, a further innovativepurpose for using either the aluminum source or the iron source is thatthe carried over trivalent cation (either aluminum or iron) with thede-toxified and de-carbonated source water is also utilized toprecipitate foulants and sulfate upon mixing with calcium hydroxide(hydrated calcium oxide), and further upon mixing with an amine solvent.

Accordingly, FIG. 5 depicts an oversimplified flow diagram for theinventive method to treat source water. Source water [1] is mixed witheither an aluminum source or an iron source [2A] to separate endotoxinsfrom acidic proteins and convert the naturally present bicarbonate insource water to carbon dioxide. Hydrophobic membranes [3] are then usedto remove endotoxins and carbon dioxide [4] from source to producede-toxified and de-carbonated source water [5]. The aluminum source isselected from the group consisting of aluminum chloride, aluminumchlorohydrate, aluminum nitrate, aluminum sulfate, aluminum acetate,aluminum formate, and combinations thereof. The iron source is selectedfrom the group consisting of iron chloride, iron chlorohydrate, ironnitrate, iron sulfate, iron acetate, iron formate, and combinationsthereof. Other aluminum or iron sources may also be used in thisinvention. The de-toxified and de-carbonated source water [5] may befurther treated to precipitate foulants and sulfate. As such, calciumhydroxide [6A] is mixed with the de-toxified and de-carbonated sourcewater [5] to form precipitates comprising foulants and sulfate (eithercalcium sulfoaluminate upon mixing with the aluminum source or calciumsulfoferrate upon mixing with the iron source) in a precipitator unit[7]. Foulants comprise magnesium, phosphates, EPS, silica, boron,transition metals, and combinations thereof. The outlet stream [10] fromthe precipitator unit [7] is fed to a filter [11] to remove theprecipitates [12] and produce de-fouled and de-sulfated source water[13]. An amine solvent [8] may also be fed to the precipitator unit [7]to accelerate precipitation by reaching a very high level ofsupersaturation within a very short period of time, which enormouslysimplifies the design of the precipitator unit [7] in terms of size (acompact modular design with a very short retention time) andeffectiveness (a fast precipitation of either calcium sulfoaluminate orcalcium sulfoferrate). The amine solvent is selected from the groupconsisting of isopropylamine, propylamine, dipropylamine,diisopropylamine, ethylamine, diethylamine, methylamine, dimethylamine,and combinations thereof. A gas [9] is fed near the bottom of theprecipitator unit [7] to recover the amine solvent. The gas is selectedfrom the group consisting of nitrogen, air, water vapor, andcombinations thereof. The recovered amine solvent [8A] is recycled forreuse in the precipitator unit [7].

Endotoxins may also be separated from acidic proteins in source water byusing calcium nitrate to reduce the pH of source water to within theisoelectric points of the acidic proteins. An additional innovativepurpose for the use of calcium nitrate is to convert the naturallypresent bicarbonate in source water to carbon dioxide. Endotoxins andcarbon dioxide are then removed from source water by hydrophobicmembranes to produce de-toxified and de-carbonated source water. Yet, afurther innovative purpose for the use of calcium nitrate is that thecarried over divalent cation (calcium) with the de-toxified andde-carbonated source water is utilized to precipitate foulants andsulfate upon mixing with either aluminum hydroxide or iron hydroxide,and further upon mixing with an amine solvent.

As such, as also shown in FIG. 5, source water [1] is mixed with calciumnitrate [2B], to separate endotoxins from acidic proteins and convertthe naturally present bicarbonate in source water to carbon dioxide.Hydrophobic membranes [3] are then used to remove endotoxins and carbondioxide [4] from source water to produce de-toxified and de-carbonatedsource water [5]. The de-toxified and de-carbonated source water [5] maybe further treated to precipitate foulants and sulfate. As such, eitheraluminum hydroxide or iron hydroxide [6B] is mixed the de-toxified andde-carbonated source water [5] to form precipitates comprising foulantsand sulfate (either calcium sulfoaluminate upon mixing with aluminumhydroxide or calcium sulfoferrate upon mixing with iron hydroxide) in aprecipitator unit [7]. Foulants comprise magnesium, phosphates, EPS,silica, boron, transition metals, and combinations thereof. The outletstream [10] from the precipitator unit [7] is fed to a filter [11] toremove the precipitates [12] and produce de-fouled and de-sulfatedsource water [13]. An amine solvent [8] may also be fed to theprecipitator unit [7] to enhance and accelerate precipitation. The aminesolvent is selected from the group consisting of isopropylamine,propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine,methylamine, dimethylamine, and combinations thereof. A gas [9] is fednear the bottom of the precipitation unit [7] to recover the aminesolvent. The gas is selected from the group consisting of nitrogen, air,water vapor, and combinations thereof. The recovered amine solvent [8A]is recycled for reuse in the precipitation unit [7].

In yet another embodiment, endotoxins are separated from acidic proteinsin source water by using an amine solvent in an anionated form to reducethe pH of source water to within the isoelectric points of acidicproteins. An additional innovative purpose for the use of the aminesolvent in the anionated form is to convert the naturally presentbicarbonate in source water to carbon dioxide. The separated endotoxinsand the converted carbon dioxide are then removed from source water byhydrophobic membranes to produce de-toxified and de-carbonated sourcewater. Yet, a further innovative purpose for using the amine solvent inthe anionated form is that the carried over amine solvent with thede-toxified and de-carbonated source water is regenerated and utilizedto enhance the precipitation of foulants and sulfate upon mixing withcalcium hydroxide and either aluminum hydroxide or iron hydroxide.

Accordingly, and as shown in FIG. 6, source water [1] is mixed with anamine solvent in an anionated form [2C] to separate endotoxins fromacidic proteins and convert the naturally present bicarbonate in sourcewater to carbon dioxide. Hydrophobic membranes [3] are then used toremove endotoxins and carbon dioxide [4] from source to producede-toxified and de-carbonated source water [5]. The amine solvent isselected from the group consisting of isopropylamine, propylamine,dipropylamine, diisopropylamine, ethylamine, diethylamine, methylamine,dimethylamine, and combinations thereof. The anionated form is selectedfrom the group consisting of chloride, chlorohydrate, nitrate, sulfate,phosphate, acetate, formate, and combinations thereof. The de-toxifiedand de-carbonated source water [5] may be further treated to precipitatefoulants and sulfate. As such, calcium hydroxide [6A], and eitheraluminum hydroxide or iron hydroxide [6B] are mixed with the de-toxifiedand de-carbonated source water [5] to regenerate the amine solvent fromit is anionated form and to form precipitates comprising foulants andsulfate (either calcium sulfoaluminate upon mixing with aluminumhydroxide or calcium sulfoferrate upon mixing with iron hydroxide) in aprecipitator unit [7]. The regenerated amine solvent within theprecipitator unit [7] accelerates the precipitation of either calciumsulfoaluminate or calcium sulfoferrate by reaching a very high level ofsupersaturation within a very short period of time, which enormouslysimplifies the design of the precipitator unit [7] in terms of size andeffectiveness. Foulants comprise magnesium, phosphates, EPS, silica,boron, transition metals, and combinations thereof. The outlet stream[10] from the precipitator unit [7] is fed to a filter [11] to removethe precipitates [12] and produce de-fouled and de-sulfated source water[13]. A gas [9] is fed near the bottom of the precipitator unit [7] torecover the amine solvent [8A]. The gas is selected from the groupconsisting of nitrogen, air, water vapor, and combinations thereof. Therecovered amine solvent [8A] is reacted with an acid [14] in line (notshown in FIG. 6) or in a vessel [15] to produce the amine solvent in theanionated form [2C] for reuse in the inventive method. The acid isselected from the group consisting of hydrochloric acid, chloralhydrate, nitric acid, sulfuric acid, phosphoric acid, acetic acid,formic acid, and combinations thereof.

In yet another embodiment, endotoxins and foulants can be precipitatedfrom source water by an amine solvent. Upon the innovative use of theamine solvent, the treated source water is simultaneously de-toxified byprecipitating endotoxins, and de-fouled by precipitating foulantscomprising magnesium, calcium, carbonate, phosphates, EPS, silica,boron, transition metals, and combinations thereof. Here, endotoxins areprecipitated with the entire proteins, and the naturally presentbicarbonate in source water is converted to carbonate and precipitatedas such by the amine solvent. If desired, the de-toxified and de-fouledsource water can further be de-sulfated upon mixing with calciumhydroxide and either aluminum hydroxide or iron hydroxide.

As such, and as depicted in FIG. 7, source water [1] is mixed with anamine solvent [8] in a first precipitator unit [7] to form firstprecipitates comprising endotoxins and foulants. A gas [9] is fed nearthe bottom of the first precipitator unit [7] to recover the aminesolvent. The recovered amine solvent [8A] is recycled for reuse in theprecipitation unit [7]. The outlet stream [10] from the firstprecipitator unit [7] is fed to a first filter [11] to remove the firstprecipitates [12] and produce de-toxified and de-fouled source water[13]. The amine solvent is selected from the group consisting ofisopropylamine, propylamine, dipropylamine, diisopropylamine,ethylamine, diethylamine, methylamine, dimethylamine, and combinationsthereof. The gas is selected from the group consisting of nitrogen, air,water vapor, and combinations thereof. Foulants comprise magnesium,calcium, carbonate, phosphates, extracellular polymeric substances(EPS), silica, boron, transition metals, and combinations thereof. Ifdesired, sulfate is then precipitated from the de-toxified and de-fouledsource water [13] by mixing with calcium hydroxide [6A], and eitheraluminum hydroxide or iron hydroxide [6B] to form second precipitatescomprising either calcium sulfoaluminate (upon mixing with aluminumhydroxide) or calcium sulfoferrate (upon mixing with iron hydroxide) ina second precipitator unit [16]. The outlet stream [17] from the secondprecipitator unit [16] is fed to a second filter [18] to remove thesecond precipitates [19] and produce de-sulfated source water [20].

The precipitation of calcium ulfoaluminate or calcium sulfoferrate takesplace based on the conditions under which it is effectivelyprecipitated. Based on the inventor's testing, the removal of sulfatefrom source water in the form of either calcium sulfoaluminate orcalcium sulfoferrate in all of the above embodiments is consistentlyover 97%. One structural formula that may generally describe certainembodiments of calcium sulfoaluminate or calcium sulfoferrate is asfollows:└ca ⁺²┘_(A) └SO ₄ ⁻²┘_(B) └M ⁺³┘_(C)[x H ₂ O]where A is the stoichiometric amount of calcium (Ca⁺²), B isstoichiometric amount of sulfate (SO₄ ⁻²), C is the stoichiometricamount of the trivalent cation (M⁺³; which is either aluminum: Al⁺³ oriron: Fe⁺³), and x is the hydration content. Depending on the amount ofsulfate in source water, the chemistry of source water, and the basicitycondition under which sulfate is precipitated in the form of eithercalcium sulfoaluminate or calcium sulfoferrate, the stoichiometric ratio(meq./L) of sulfate to calcium (B/A) is 0.2 to 0.5, the stoichiometricratio (meq./L) of sulfate to the trivalent cation (13/C) is 0.5 to 1.5,and the hydration content (x) is 24 to 32.

Source water is selected from the group consisting of domesticwastewater, an effluent stream from a wastewater treatment plant, aneffluent stream from a wastewater treatment and reclamation plant, areverse osmosis reject stream from a wastewater treatment andreclamation plant, a nanofiltration reject stream from a wastewatertreatment and reclamation plant, an ultrafiltration reject stream from awastewater treatment and reclamation plant, a microfiltration rejectstream from a wastewater treatment and reclamation plant, sludgethickening/dewatering reject streams from a wastewater treatment plant,sludge thickening/dewatering reject streams from a wastewater treatmentand reclamation plant, produced water, agricultural drainage water, minedrainage water, and combinations thereof.

It should be noted that when source water, for example, comprisesproduced water, the hydrophobic membranes [3] as shown in FIGS. 5 and 6would additionally serve as a de-oiling step. The immiscibility of oilcontent in such source water allows it to permeate through thehydrophobic membranes (as a membranes' wetting fluid) whereas thehydrophobic membranes repel water (as a membranes' non-wetting fluid)[e.g., Bader, U.S. Pat. Nos. 6,365,051; 7,789,159; 7,934,551; 7,963,338;and 8,915,301]. The treated water by the inventive methods may then beused, for example, as: (1) low salinity fracturing water in shale andsand formations; (2) injecting water for improved oil recovery; and (3)feeding water to generate steam for enhanced oil recovery.

TABLE 1 Effluent and RO Reject Streams from WWTRP. Species ActivatedSludge Effluent Stream RO Reject Stream (mg/L) Average (Range) Average(Range) Na⁺ 156.3 (124.2-204.9) 950.9 (573.0-1,275.0) K⁺ 12.6(11.3-14.6) 79.8 (69.0-92.6) Mg⁺² 11.9 (9.4-14.7) 76.2 (58.9-90.5) Ca⁺²45.0 (40.3-52.5) 290.8 (244.6-328.7) Sr⁺² 0.61 (0.47-0.70) 3.7 (3.0-4.1)Ba⁺² 0.02 (0.01-0.03) 0.12 (0.06-0.14) Fe⁺² 0.08 (0.01-0.20) 0.14(0.11-0.25) Cl⁻ 239.7 (156.9-370.1) 1,462.2 (937.2-1,962.9) HCO₃ ⁻ 97.8(69.8-125.2) 416.6 (328.7-582.5) NO₃ ⁻ 2.8 (1.4-4.5) 13.4 (3.0-19.0) SO₄⁻² 120.3 (104.8-149.7) 760.1 (606.3-868.6) PO₄ ⁻³ 8.6 (2.6-14.5) 47.7(36.8-66.7) TP 11.5 (8.8-16.1) 63.6 (48.7-88.4) SiO₂ 2.1 (1.6-2.5) 13.3(9.9-15.8) B 0.27 (0.19-0.36) 0.57 (0.25-0.73) TDS 690.8 (564.9-821.5)4,096.9 (3,251.0-4,753.5) TH 161.5 (139.4-178.5) 1,040.6 (854.1-1,190.0)COD 319.0 (155.0-690.0) 379.0 (168.0-789.0) pH 6.7 (6.5-7.3) 7.1(6.8-7.8) T (° C.) 39 (35-40) TH: Total Hardness.

TABLE 2 Endotoxins in WWTRP and WWTP with Recycling Rejects. EndotoxinsFlow Rate Endotoxins Load Stream (EU/mL) (m³/day) (EU/day) WWTRP withRecycling to Influent Influent [I] 3,400 375,000 1.28E15 Recycled toInfluent 24,900 57,450 1.43E15 UF Reject [UF-R] 28,600 41,700 1.19E15Thickener Reject [T-R] 16,100 12,750 2.05E14 Dewatering Reject [D-R]10,700 3,000 3.21E13 Mixed Influent [MI] 6,200 432,450 2.68E15 Effluent[E] 5,200 416,700 2.17E15 UF Product [UF-P] 2,600 375,000 9.75E14 ROProduct [RO-P] 400 318,750 1.28E14 RO Reject [RO-R] 15,100 56,2508.49E14 (Disposal) WWTP with Recycling to Influent Influent [I] 3,400375,000 1.28E15 Recycled to Influent 9,100 13,000 1.18E14 ThickenerReject [T-R] 9,600 10,800 1.04E14 Dewatering Reject [D-R] 6,300 2,2001.39E13 Mixed Influent [MI] 3,600 388,000 1.40E15 Effluent [E] 2,600376,000 9.78E14

TABLE 3 Endotoxins in WWTRP with Partial Recycling and without RecyclingRejects. Endotoxins Flow Rate Endotoxins Load Stream (EU/mL) (m³/day)(EU/day) WWTRP with Partial Recycling to Influent (as in WWTP) Influent[I] 3,400 375,000 1.28E15 Recycled to Influent 9,100 13,000 1.18E14Thickener Reject [T-R] 9,600 10,800 1.04E14 Dewatering Reject [D-R]6,300 2,200 1.39E13 Mixed Influent [MI] 3,600 388,000 1.40E15 Effluent[E] 2,600 376,000 9.78E14 UF Product [UF-P] 1,300 338,400 4.40E14 ROProduct [RO-P] 250 287,600 7.19E13 Combined Rejects (Disposal) 10,30088,400 9.06E14 UF Reject [UF-R] 14,300 37,600 5.38E14 RO Reject [RO-R]7,250 50,800 3.68E14 WWTRP without Recycling to Influent Influent [I]3,400 375,000 1.28E15 Effluent [E] 2,400 356,000 8.54E14 UF Product[UF-P] 1,200 320,400 3.84E14 RO Product [RO-P] 200 272,300 5.45E13Combined Rejects (Disposal) 9,400 94,300 8.85E14 UF Reject [UF-R] 13,20035,600 4.70E14 RO Reject [RO-R] 6,800 48,100 3.27E14 Thickener Reject[T-R] 8,900 8,600 7.65E13 Dewatering Reject [D-R] 5,900 2,000 1.19E13

What is claimed is:
 1. A method for treating source water, said methodcomprising the steps of: (i) separating endotoxins and carbon dioxidefrom said source water by (a) mixing an aluminum source or an ironsource with said source water to separate said endotoxins from acidicproteins and convert naturally present bicarbonate in said source waterto said carbon dioxide; and (b) removing said endotoxins and said carbondioxide from said source water by hydrophobic membranes to producede-toxified and de-carbonated source water; and (ii) separating foulantsand sulfate from said de-toxified and de-carbonated source water by (a)mixing calcium hydroxide with said de-toxified and de-carbonated sourcewater to form precipitates comprising calcium sulfoaluminate or calciumsulfoferrate in a precipitator unit; and (ii) removing said precipitatesby a filter.
 2. The method of claim 1, wherein said aluminum source isselected from the group consisting of aluminum chloride, aluminumchlorohydrate, aluminum nitrate, aluminum sulfate, aluminum acetate,aluminum formate, and combinations thereof.
 3. The method of claim 1,wherein said iron source is selected from the group consisting of ironchloride, iron chlorohydrate, iron nitrate, iron sulfate, iron acetate,iron formate, and combinations thereof.
 4. The method of claim 1,wherein said foulants comprise magnesium, phosphates, extracellularpolymeric substances (EPS), silica, boron, transition metals, andcombinations thereof.
 5. The method of claim 1, wherein step (ii)(a)further comprises the step of mixing an amine solvent, said aminesolvent is selected from the group consisting of isopropylamine,propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine,methylamine, dimethylamine, and combinations thereof.
 6. The method ofclaim 5, comprising the step of recovering said amine solvent by a gas,said gas is selected from the group consisting of nitrogen, air, watervapor, and combination thereof.
 7. The method of claim 1, wherein saidsource water is selected from the group consisting of domesticwastewater, an effluent stream from a wastewater treatment plant, aneffluent stream from a wastewater treatment and reclamation plant, areverse osmosis reject stream from a wastewater treatment andreclamation plant, a nanofiltration reject stream from a wastewatertreatment and reclamation plant, an ultrafiltration reject stream from awastewater treatment and reclamation plant, a microfiltration rejectstream from a wastewater treatment and reclamation plant, sludgethickening/dewatering reject streams from a wastewater treatment plant,sludge thickening/dewatering reject streams from a wastewater treatmentand reclamation plant, produced water, agricultural drainage water, minedrainage water, and combinations thereof.
 8. A method for treatingsource water, said method comprising the steps of: (i) separatingendotoxins and carbon dioxide from said source water by (a) mixingcalcium nitrate with said source water to separate said endotoxins fromacidic proteins and convert naturally present bicarbonate in said sourcewater to said carbon dioxide; and (b) removing said endotoxins and saidcarbon dioxide from said source water by hydrophobic membranes toproduce de-toxified and de-carbonated source water; and (ii) separatingfoulants and sulfate from said de-toxified and de-carbonated sourcewater by (a) mixing aluminum hydroxide or iron hydroxide with saidde-toxified and de-carbonated source water to form precipitatescomprising either calcium sulfoaluminate or calcium sulfoferrate in aprecipitator unit; and (b) removing said precipitates by a filter. 9.The method of claim 8, wherein said foulants comprise magnesium,phosphates, extracellular polymeric substances (EPS), silica, boron,transition metals, and combinations thereof.
 10. The method of claim 8,wherein step (ii)(a) further comprises the step of mixing an aminesolvent, said amine solvent is selected from the group consisting ofisopropylamine, propylamine, dipropylamine, diisopropylamine,ethylamine, diethylamine, methylamine, dimethylamine, and combinationsthereof.
 11. The method of claim 10, comprising the step of recoveringsaid amine solvent by a gas, said gas is selected from the groupconsisting of nitrogen, air, water vapor, and combinations thereof. 12.The method of claim 8, wherein said source water is selected from thegroup consisting of domestic wastewater, an effluent stream from awastewater treatment plant, an effluent stream from a wastewatertreatment and reclamation plant, a reverse osmosis reject stream from awastewater treatment and reclamation plant, a nanofiltration rejectstream from a wastewater treatment and reclamation plant, anultrafiltration reject stream from a wastewater treatment andreclamation plant, a microfiltration reject stream from a wastewatertreatment and reclamation plant, sludge thickening/dewatering rejectstreams from a wastewater treatment plant, sludge thickening/dewateringreject streams from a wastewater treatment and reclamation plant,produced water, agricultural drainage water, mine drainage water, andcombinations thereof.
 13. A method for treating source water, saidmethod comprising the steps of: (i) separating endotoxins and carbondioxide from said source water by (a) mixing an amine solvent in ananionated form with said source water to separate said endotoxins fromacidic proteins and convert naturally present bicarbonate in said sourcewater to said carbon dioxide; and (b) removing said endotoxins and saidcarbon dioxide from said source water by hydrophobic membranes toproduce de-toxified and de-carbonated source water; and (ii) separatingfoulants and sulfate from said de-toxified and de-carbonated sourcewater by (a) mixing calcium hydroxide, and aluminum hydroxide or ironhydroxide, with said de-toxified and de-carbonated source water toregenerate said amine solvent and to form precipitates comprisingcalcium sulfoaluminate or calcium sulfoferrate in a precipitator unit;and (b) removing said precipitates by a filter.
 14. The method of claim13, wherein said amine solvent is selected from the group consisting ofisopropylamine, propylamine, dipropylamine, diisopropylamine,ethylamine, diethylamine, methylamine, dimethylamine, and combinationsthereof.
 15. The method of claim 13, wherein said anionated form isselected from the group consisting of chloride, chlorohydrate, nitrate,sulfate, phosphate, acetate, formate, and combinations thereof.
 16. Themethod of claim 13, wherein said foulants comprise magnesium,phosphates, extracellular polymeric substances (EPS), silica, boron,transition metals, and combinations thereof.
 17. The method of claim 13,comprising the step of recovering said amine solvent by a gas, said gasis selected from the group consisting of nitrogen, air, water vapor, andcombinations thereof.
 18. The method of claim 17, comprising the step ofreacting the recovered said amine solvent with an acid to produce saidamine solvent in said anionated form.
 19. The method of claim 18,wherein said acid is selected from the group consisting of hydrochloricacid, chloral hydrate, nitric acid, sulfuric acid, phosphoric acid,acetic acid, formic acid, and combinations thereof.
 20. The method ofclaim 13, wherein said source water is selected from the groupconsisting of domestic wastewater, an effluent stream from a wastewatertreatment plant, an effluent stream from a wastewater treatment andreclamation plant, a reverse osmosis reject stream from a wastewatertreatment and reclamation plant, a nanofiltration reject stream from awastewater treatment and reclamation plant, an ultrafiltration rejectstream from a wastewater treatment and reclamation plant, amicrofiltration reject stream from a wastewater treatment andreclamation plant, sludge thickening/dewatering reject streams from awastewater treatment plant, sludge thickening/dewatering reject streamsfrom a wastewater treatment and reclamation plant, produced water,agricultural drainage water, mine drainage water, and combinationsthereof.
 21. A method for treating source water, said method comprisingthe steps of: (i) separating endotoxins and foulants from said sourcewater by (a) mixing an amine solvent with said source water to formfirst precipitates comprising said endotoxins and said foulants in afirst precipitator unit; and (b) removing said first precipitates by afirst filter to produce de-toxified and de-fouled source water; and (ii)separating sulfate from said de-toxified and de-fouled source water by(a) mixing said de-toxified and de-fouled source water with calciumhydroxide, and aluminum hydroxide or iron hydroxide, to form secondprecipitates comprising calcium sulfoaluminate or calcium sulfoferratein a second precipitator unit; and (b) removing said second precipitatesby a second filter.
 22. The method of claim 21, wherein said aminesolvent is selected from the group consisting of isopropylamine,propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine,methylamine, dimethylamine, and combinations thereof.
 23. The method ofclaim 21, comprising the step of recovering said amine solvent by a gas,said gas is selected from the group consisting of nitrogen, air, watervapor, and combinations thereof.
 24. The method of claim 21, whereinsaid foulants comprise magnesium, calcium, carbonate, phosphates,extracellular polymeric substances (EPS), silica, boron, transitionmetals, and combinations thereof.
 25. The method of claim 21, whereinsaid source water is selected from the group consisting of domesticwastewater, an effluent stream from a wastewater treatment plant, aneffluent stream from a wastewater treatment and reclamation plant, areverse osmosis reject stream from a wastewater treatment andreclamation plant, a nanofiltration reject stream from a wastewatertreatment and reclamation plant, an ultrafiltration reject stream from awastewater treatment and reclamation plant, a microfiltration rejectstream from a wastewater treatment and reclamation plant, sludgethickening/dewatering reject streams from a wastewater treatment plant,sludge thickening/dewatering reject streams from a wastewater treatmentand reclamation plant, produced water, agricultural drainage water, minedrainage water, and combinations thereof.